Policy control method and system for accessing fixed broadband access network

ABSTRACT

The disclosure provides a policy control method and a policy control system for accessing a fixed broadband access network. The policy control method includes: a FMC PF used for sensing the access of UE to a fixed broadband access network is set in a mobile network which a user requests to be accessed to; after the FMC PF receives a trigger message from an ePDG, the FMC PF requests a BPCF to establish a policy session, and the BPCF performs, policy control according to the information of the fixed broadband access network accessed by the UE. It can be seen from the method of the disclosure that when the UE is accessed to the 3GPP through the fixed broadband access network, the FMC PF senses a gateway control session establishment request message or a DHCP request message from the ePDG, so that a PCRF of the 3GPP access network accessed by the UE is triggered to send a policy session request to the BPCF. In this way, in the case that the fixed broadband access network fails to sense the access of the UE or that the fixed broadband access network does not support 3GPP-based access authentication in the conventional art where the UE is accessed to a 3GPP core network through the fixed broadband access network, QoS control is achieved for the access of the UE, and thus QoS guarantee is provided to the entire transmission path of data.

TECHNICAL FIELD

The disclosure relates to intercommunication between 3GPP and BroadbandForum (BBF), and in particular to a policy control method and a policycontrol system for accessing a fixed broadband access network.

BACKGROUND

FIG. 1 shows an architecture diagram of a current 3GPP Evolved PacketSystem (EPS). The EPS network architecture in a non-roaming scene shownin FIG. 1 includes an Evolved Universal Terrestrial Radio Access Network(E-UTRAN), a Mobility Management Entity (MME), a Serving Gateway (S-GW),a Packet Data Network Gateway (P-GW, also called PDN GW), a HomeSubscriber Server (HSS), a Policy and Charging Rules Function (PCRF) andother support nodes.

The PCRF is the core of Policy and Charging Control (PCC) and isresponsible for making policies and making charging rules. The PCRFprovides network control rules which are based on service data stream,wherein the network control includes the detection, gating control,Quality of Service (QoS) control of the service data stream, thecharging rules based on data stream and so on. The PCRF sends the policyand charging rules made by the PCRF itself to a Policy and ChargingEnforcement Function (PCEF) to execute, meanwhile the PCRF has toguarantee the consistency between the rules and the subscriptioninformation of a user. The basis for the PCRF to make policy andcharging rules includes: acquiring information related to service fromApplication Function (AF), acquiring the policy and charging controlsubscription information of a user from a Subscription ProfileRepository (SPR), and acquiring network information related to bearerfrom the PCEF.

The EPS supports the interconnection with a non-3GPP system, which isimplemented through S2a/b/c interfaces, wherein the P-GW serves as ananchor between the 3GPP system and the non-3GPP system. As shown in FIG.1, the non-3GPP system is divided into trusted non-3GPP IP access anduntrusted non-3GPP IP access, wherein the trusted non-3GPP IP access isconnected directly to the P-GW via the S2a interface; while theuntrusted non-3GPP IP access needs to be connected to the P-GW throughan Evolved Packet Data Gateway (ePDG). The interface between the ePDGand the P-GW is the S2b interface, and Internet Protocol Security(IPSec) is adopted between the User Equipment (UE) and the ePDG toperform encryption protection on signalling and data. The S2c interfaceprovides user-plane-related control and mobility support between the UEand the P-GW, wherein the supported mobility management protocol isMobile IPv6 support for dual stack Hosts and Routers (DSMIPv6).

At present, many operators focus on Fixed Mobile Convergence (FMC) andresearch the intercommunication between 3GPP and BBF. For the scene thata user accesses a mobile core network through the BBF (that is, fixedbroadband access network), it is needed to guarantee the QoS on theentire transmission path of data (the data would be transmitted throughthe fixed network and the mobile network). In the conventional art,interaction is implemented through the PCRF and a Broadband PolicyControl Framework (BPCF) in the BBF access (that is, fixed broadbandaccess network), so as to realize QoS guarantee. The BPCF is the policycontrol framework in the fixed broadband access network. For a resourcerequest message from the PCRF, the BPCF performs resource admissioncontrol according to the network policy and subscription information ofthe fixed broadband access network, or forwards the resource requestmessage to other network elements (for example, Broadband NetworkGateway (BNG)) of the fixed broadband access network), and then thisnetwork element performs resource admission control (that is to say, theBPCF delegates other network elements to perform resource admissioncontrol). For example, when a UE accesses a 3GPP core network through aWide Local Area Network (WLAN), in order to guarantee that the totalbandwidth of the services accessed by all UEs which access the corenetwork through one WLAN access line does not exceed the bandwidth ofthis line (for example, subscribed bandwidth or maximum physicalbandwidth supported by this line), the PCRF needs to interact with theBPCF when performing QoS authorization, so that the fixed broadbandaccess network performs the resource admission control. During specificimplementation, the PCRF provides QoS rules for the BPCF and the fixedbroadband access network performs admission control according to the QoSrules.

FIG. 2 shows a diagram illustrating the architecture in which a UEaccesses a 3GPP core network through a fixed broadband access networkaccording to the conventional art.

As shown in FIG. 2, the fixed broadband access network serves as theuntrusted non-3GPP access. In the architecture shown in FIG. 2, afterthe UE is accessed to the fixed broadband access network, a BroadbandRemote Access Server (BRAS)/BNG would perform 3GPP-based accessauthentication, meanwhile the BPCF of the BBF actively initiates an S9*session to interact with the PCRF of the 3GPP. Thus, the PCRF caninteract with the BPCF when performing QoS authorization; and then theBPCF performs the resource admission control or delegates other networkelements of the fixed broadband access network to perform the resourceadmission control.

However, in some scenes, the fixed broadband access network can notalways sense the access of UE, or the fixed broadband access networkdoes not support the 3GPP-based access authentication. In this case, theBPCF can not initiate the S9* session actively and thus can notimplement the QoS control on the access of UE.

SUMMARY

In view of the above, the main purpose of the disclosure is to provide apolicy control method and a policy control system for accessing a fixedbroadband access network, which can implement the QoS control on theaccess of UE and thus provide QoS guarantee to the entire transmissionpath of data in the case that the fixed broadband access network failsto sense the access of UE or that the fixed broadband access networkdoes not support 3GPP-based access authentication.

In order to achieve the purpose above, the technical scheme of thedisclosure is realized as follows.

The disclosure provides a policy control method for accessing a fixedbroadband access network, which includes: an FMC PF is set in a mobilenetwork which a user requests to be accessed to,

after the FMC PF receives a trigger message from an ePDG, the FMC PFrequests a BPCF in the fixed broadband access network to establish apolicy control session; and

the fixed broadband access network performs admission control accordingto QoS rules or QoS information transmitted from the FMC PF through thepolicy control session.

The FMC PF may serve as a separate function entity, or may be integratedin a PCRF.

The trigger message received by the FMC PF from the ePDG may be: agateway control session establishment message carrying IPSec externaltunnel information or a Dynamic Host Configuration Protocol (DHCP)request message carrying IPSec external tunnel information, wherein theIPSec external tunnel information may include a UE local IP addressreceived by the ePDG.

The processing that the FMC PF requests the BPCF to establish a policycontrol session may include: the FMC PF determines the BPCF of the fixedbroadband access network accessed by the UE or the entry point of thefixed broadband access network in which the BPCF is located according tothe UE local IP address, and sends an S9* session establishment messageto the BPCF, wherein the S9* session establishment message may carriedwith the IPSec external tunnel information.

The IPSec external tunnel information may include a source port number.

When the user is a non-roaming user, the mobile network which the userrequests to be accessed to may the Public Land Mobile Network (PLMN) towhich the user belongs; when the user is a roaming user, the mobilenetwork which the user requests to be accessed to may be the PLMN thatthe user visits.

The processing of requesting to establish a policy control session andthe processing that the fixed broadband access network performsadmission control may include: after the FMC PF acquires PCC rules, QoSrules or a QoS request, the FMC PF transmits the QoS rules or QoSinformation to the BPCF through the policy control session.

The FMC PF may serve as a separate function entity, and the processingthat the FMC PF acquires the QoS rules or the QoS information mayinclude: the FMC PF acquires the PCC rules or the QoS rules from a PCRF;or the FMC PF acquires the QoS request from the ePDG.

The FMC PF may be integrated in the PCRF, and the processing that theFMC PF acquires the PCC rules, the QoS rule or the QoS request mayinclude: when the user is a non-roaming user, the PCRF makes the PCCrules and/or the QoS rules; when the user is a roaming user, the PCRFacquires the PCC rules or the QoS rules from a PCRF of the PLMN to whichthe user belongs; or

the PCRF acquires the QoS request from the ePDG.

The processing that the fixed broadband access network performs resourceadmission control according to a request may include:

if the BPCF receives a request for allocating bandwidth resource GBR(Guaranteed Bit Rate), the fixed broadband access network performs theresource admission control according to the currently availablebandwidth of a subscribed fixed-network line:

-   -   when the rest available bandwidth is greater than or equal to        the GBR, the fixed broadband access network accepts the request        of the FMC PF of the mobile network which the user requests to        be accessed to; the fixed broadband access network returns an        acceptance acknowledgement message to the FMC PF of the mobile        network which the user requests to be accessed to; and the fixed        broadband access network deducts the GBR from the currently        available bandwidth of the subscribed fixed-network line,    -   when the rest available bandwidth is less than the GBR, the        fixed broadband access network rejects the request of the FMC PF        of the mobile network which the user requests to be accessed to;        and the fixed broadband access network returns a rejection        message to the FMC PF of the mobile network which the user        requests to be accessed to, wherein the rejection message may be        carried with the bandwidth that the FMC PF can accept,        If the BPCF receives a request for releasing the bandwidth        resource GBR, the BPCF returns an acceptance acknowledgement        message; and the fixed broadband access network adds the GBR to        the currently available bandwidth of the subscribed        fixed-network line.

If the FMC PF receives the rejection message, the method may furtherinclude: the FMC PF performs resource pre-emption according to anAllocation and Retention Priority (ARP).

The disclosure provides a policy control system for accessing a fixedbroadband access network, which at least includes an ePDG, an FMC PF anda BPCF, wherein

the ePDG is configured to send a trigger message to the FMC PF;the FMC PF is set in a mobile network which a user requests to beaccessed to and is configured to receive the trigger message from theePDG and to request the BPCF to establish a policy control session; andthe BPCF is configured to receive the request from the FMC PF and toperform admission control according to QoS rules or QoS informationtransmitted through the policy control session or to delegate anothernetwork element of the fixed broadband access network to perform theadmission control.

The FMC PF may be configured to acquire PCC rules, QoS rules or a QoSrequest containing GBR, and to transmit the QoS rules or QoS informationto the BPCF through the policy control session.

The FMC PF may serve as a separate function entity,

the system may further include a PCRF which is configured to provide thePCC rules or the QoS rules to the FMC PF; orthe ePDG may be configured to provide the QoS request to the FMC PF.

The FMC PF may be integrated in a PCRF,

the PCRF may be configured to make PCC rules or QoS rules when the useris a non-roaming user, and to acquire the PCC rules or the QoS rulesfrom a PCRF of the PLMN to which the user belongs when the user is aroaming user; orthe PCRF may be configured to acquire the QoS request from the ePDG.

When the FMC PF receives a rejection message from the BPCF, the FMC PFmay be configured to perform resource pre-emption according to an ARP.

From the above technical scheme provided by the disclosure, it can beseen that an FMC PF used for sensing the access of a UE to a fixedbroadband access network is set in a mobile network which a userrequests to be accessed to; after the FMC PF receives a trigger messagefrom an ePDG, the FMC PF requests a BPCF to establish a policy session,and the BPCF performs policy control according to the information of thefixed broadband access network accessed by the UE. From theimplementation of the method of the disclosure, it can be seen that whenthe UE is accessed to the 3GPP through the fixed broadband accessnetwork, the FMC PF senses a gateway control session establishmentrequest message or a DHCP request message from the ePDG, so that thePCRF of the 3GPP access network accessed by the UE is triggered to senda policy session request to the BPCF. In this way, in the case that thefixed broadband access network fails to sense the access of the UE orthat the fixed broadband access network does not support 3GPP-basedaccess authentication in the conventional art where the UE is accessedto a 3GPP core network through the fixed broadband access network, QoScontrol is achieved for the access of the UE, and thus QoS guarantee isprovided to the entire transmission path of data.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an architecture diagram of an existing EPS;

FIG. 2 shows a diagram illustrating the architecture in which a UEaccesses a 3GPP core network through a fixed broadband access networkaccording to the conventional art;

FIG. 3 shows a flowchart of a policy control method for accessing afixed broadband access network according to the disclosure;

FIG. 4 shows a structure diagram of a policy control system foraccessing a fixed broadband access network according to the disclosure;

FIG. 5 shows a diagram illustrating the home routed roaming scene inwhich a UE is accessed to a 3GPP core network through an untrusted fixedbroadband access network according to the disclosure, in which a PMIPv6protocol is adopted between an ePDG and a P-GW;

FIG. 6 shows an attachment flowchart in which a UE is accessed to a 3GPPcore network through an untrusted fixed broadband access network basedon the architecture shown in FIG. 5;

FIG. 7 shows a diagram illustrating the home routed roaming scene inwhich a UE is accessed to a 3GPP core network through an untrusted fixedbroadband access network according to the disclosure, in which a GTPprotocol is adopted between an ePDG and a P-GW;

FIG. 8 shows an attachment flowchart in which a UE is accessed to a 3GPPcore network through an untrusted fixed broadband access network basedon the architecture shown in FIG. 7;

FIG. 9 shows a diagram illustrating the home routed roaming scene inwhich a UE is accessed to a 3GPP core network through an untrusted fixedbroadband access network according to the disclosure, in which the UEadopts a DSMI Pv6 protocol;

FIG. 10 shows an attachment flowchart in which a UE is accessed to a3GPP core network through an untrusted fixed broadband access networkbased on the architecture shown in FIG. 9;

FIG. 11 shows a diagram illustrating the local breakout roaming scene inwhich a UE is accessed to a 3GPP core network through an untrusted fixedbroadband access network according to the disclosure, in which a GTP orPMIPv6 protocol is adopted between an ePDG and a P-GW;

FIG. 12 shows an attachment flowchart in which a UE attachment a 3GPPcore network through an untrusted fixed broadband access network basedon the architecture shown in FIG. 11;

FIG. 13 shows a diagram illustrating the local breakout roaming scene inwhich a UE is accessed to a 3GPP core network through an untrusted fixedbroadband access network according to the disclosure, in which the UEadopts a DSMIPv6 protocol to perform access;

FIG. 14 shows an attachment flowchart in which a UE is accessed to a3GPP core network through an untrusted fixed broadband access networkbased on the architecture shown in FIG. 13;

FIG. 15 shows a diagram illustrating the non-roaming scene in which a UEis accessed to a 3GPP core network through an untrusted fixed broadbandaccess network according to the disclosure, in which a GTP or PMIPv6protocol is adopted between an ePDG and a P-GW;

FIG. 16 shows a diagram illustrating the non-roaming scene in which a UEis accessed to a 3GPP core network through an untrusted fixed broadbandaccess network according to the disclosure, in which the UE adopts aDSMIPv6 protocol to perform access;

FIG. 17 shows a flowchart in which a PCRF requests a BPCF to perform QoSauthorization when making polices in the home routed roaming sceneaccording to the disclosure;

FIG. 18 shows a flowchart in which a PCRF requests a BPCF to perform QoSauthorization when making polices in the local breakout roaming sceneaccording to the disclosure; and

FIG. 19 shows a flowchart in which an H-PCRF requests a BPCF to performQoS authorization when making polices in the home routed roaming sceneaccording to the disclosure.

DETAILED DESCRIPTION

FIG. 3 shows a flowchart of a policy control method for accessing afixed broadband access network according to the disclosure. As shown inFIG. 3, the method includes the following steps.

Step 300: an FMC Policy Function (PF) is set in a mobile network which auser requests to be accessed to.

The FMC PF may serve as a separate function entity, or may be integratedin a PCRF.

When the user is a non-roaming user, the mobile network which the userrequests to be accessed to is the PLMN to which the user belongs; whenthe user is a roaming user, the mobile network which the user requeststo be accessed to is the PLMN that the user visits.

Step 301: after receiving a trigger message from an ePDG, the FMC PFrequests a BPCF to establish a policy control session.

After a UE is accessed to a fixed broadband access network system, thefixed broadband access network system would allocate a local IP addressfor the UE, then the UE initiates an Internet Key Exchange version 2(IKEv2) tunnel establishment process and adopts an ExtensibleAuthentication Protocol (EAP) to perform authentication. For a roamingscene, the ePDG further interacts with an Authentication, Authorizationand Accounting Server (AAA Server, which also can interact with an HSS)through an AAA Proxy to complete the EAP authentication.

After the EAP authentication is passed, the ePDG sends the FMC PF agateway control session establishment message or a DHCP request messageto, in which user ID, PDN ID and IPSec external tunnel information arecarried. The IPSec external tunnel information includes the sourceaddress and the source port of the IKEv2 signalling sent from the UE andreceived by the ePDG. It should be noted that the source address and thesource port received by the ePDG probably are different from those sentby the UE because the IKEv2 signalling might be processed with NetworkAddress Translator (NAT) traversal. For ease of description, the sourceaddress of the UE acquired by the ePDG in this paper (including bothconditions of NAT existing between the UE and the ePDG and NAT notexisting between the UE and the ePDG) is called the UE local IP address.For the condition of NAT not existing between the UE and the ePDG, theUE local IP address may be applied to the fixed broadband access networkto locate the UE; if NAT exists, the local address of the UE and thesource port number may be applied to the fixed broadband access networkto locate the UE. If there is no NAT detected, the IPSec external tunnelinformation contains the source IP address only.

The FMC PF determines the BPCF of the fixed broadband access networkaccessed by the UE or the entry point of the fixed broadband accessnetwork in which the BPCF is located according to the source address(for example, IP address) in the IPSec external tunnel information, andsends an S9* session establishment message to the BPCF, wherein the S9*session establishment message is carried with the source IP address andthe source port number contained in the IPSec external tunnelinformation (NAT exists if NAT is detected).

Step 302: the fixed broadband access network performs admission controlaccording to QoS rules or QoS information transmitted from the FMC PFthrough the policy control session.

The fixed broadband access network performs admission control accordingto the QoS rules or QoS information and the available bandwidth resourceof the line of the fixed broadband access network accessed by the user,or delegates other network elements of the fixed broadband accessnetwork to perform resource admission control.

It can be seen from the implementation of the method of the disclosurethat, when the UE is accessed to the 3GPP through the fixed broadbandaccess network, the FMC PF senses the trigger message from the ePDG(receiving the gateway control session establishment request message orDHCP request message), so that the FMC PF of the 3GPP access networkaccessed by the UE is triggered to send a policy session request to theBPCF. In this way, in the case that the fixed broadband access networkfails to sense the access of the UE or that the fixed broadband accessnetwork does not support 3GPP-based access authentication in thearchitecture of the conventional art where the UE is accessed to the3GPP core network through the fixed broadband access network, QoScontrol is achieved for the access of the UE, and thus QoS guarantee isprovided to the entire transmission path of data.

After the UE is accessed to the 3GPP core network through the fixedbroadband access network, the policy may change. For instance, the PCRF(or a Home PCRF (H-PCRF) in a roaming scene) makes a policy afterreceiving service information provided by an AF or a resourcemodification request message initiated by the UE, and the BPCF isrequested to perform admission control after the FMC PF receives changedPCC rules, QoS Rules or QoS request, then the fixed broadband accessnetwork performs resource admission control according to the request(that is, the BPCF performs resource admission control or the BPCFdelegates other network elements to perform resource admission control).

FIG. 4 shows a structure diagram of a policy control system foraccessing a fixed broadband access network according to the disclosure.As shown in FIG. 4, the system at least includes an ePDG, an FMC PF anda BPCF, wherein

the ePDG is configured to send a trigger message to the FMC PF;the FMC PF, provided in a mobile network which a user requests to beaccessed to, is configured to receive the trigger message from the ePDGand to request the BPCF to establish a policy control session; whereinthe FMC PF may serve as a separate function entity, or may be integratedin a PCRF;the BPCF is configured to receive the request from the FMC PF and toperform admission control according to QoS rules or QoS informationtransmitted through the policy control session or to delegate othernetwork elements of the fixed broadband access network to performadmission control.

The FMC PF is specifically configured to acquire PCC rules, QoS rules ora QoS request containing GBR, and to transmit the QoS information to theBPCF through the policy control session.

When the FMC PF serves as a separate function entity, the systemprovided by the disclosure further includes a PCRF which is configuredto provide the PCC rules or QoS rules to the FMC PF; or

the ePDG is further configured to provide the QoS request to the FMC PF.

When the FMC PF is integrated in the PCRF, the PCRF is configured tomake the PCC rules or QoS rules when the user is a non-roaming user, andto acquire the PCC rules or QoS rules from the PCRF of the PLMN to whichthe user belongs when the user is a roaming user; or

the PCRF is configured to acquire the QoS request from the ePDG.

The method of the disclosure is described below in further detail inconjunction with embodiments.

FIG. 5 shows a diagram illustrating the home routed roaming scene inwhich a UE is accessed to a 3GPP core network through an untrusted fixedbroadband access network according to the disclosure, in which a PMIPv6protocol is adopted between an ePDG and a P-GW. In FIG. 5, except theaddition of the FMC PF, other network entities and the connectionrelationships therebetween are the same as those in the conventionalart. Therefore, FIG. 5 is easily understood for those skilled in the artand no further description is provided here.

FIG. 6 shows an attachment flowchart in which a UE is accessed to a 3GPPcore network through an untrusted fixed broadband access network basedon the architecture shown in FIG. 5. Referring to FIG. 5 and FIG. 6,supposing an FMC PF is provided in a V-PCRF as the function enhancementof the V-PCRF in this embodiment, the specific implementation includesthe following steps.

Step 601: after the UE is accessed to the fixed broadband access networksystem, the fixed broadband access network system allocates a local IPaddress for the UE. The UE initiates an IKEv2 tunnel establishmentprocess and adopts an EAP to perform authentication. Since thisembodiment is in a roaming scene, the ePDG interacts with an AAA Server(the AAA Server further interacts with an HSS) through an AAA Proxy tocomplete the EAP authentication.

Step 602: the ePDG sends the V-PCRF a gateway control sessionestablishment message, in which the user ID, PDN ID and IPSec externaltunnel information are carried, wherein the IPSec external tunnelinformation includes the source address and the source port of the IKEv2signalling sent from the UE and received by the ePDG.

Since the IKEv2 signalling might be processed with NAT traversal, thesource address and the source port received by the ePDG probably aredifferent from those sent by the UE. For ease of description, the sourceaddress of the UE acquired by the ePDG (including both conditions of NATexisting between the UE and the ePDG and NAT not existing between the UEand the ePDG) is called the UE local IP address. For the condition ofNAT not existing between the UE and the ePDG, the UE local IP addressmay be applied to the fixed broadband access network to locate the UE;if NAT exists, the local address of the UE and the source port numbermay be applied to the fixed broadband access network to locate the UE.If there is no NAT detected, the IPSec external tunnel informationcontains the source IP address only.

It should be noted that Step 602 includes Step 602 a and Step 602 b ifthe FMC PF serves as a separate network element entity.

Step 602 a: the ePDG sends the FMC PF the gateway control sessionestablishment message, in which the user ID, the PDN ID and the IPSecexternal tunnel information are carried.

Step 602 b: the FMC PF sends the V-PCRF the gateway control sessionestablishment message, in which the user ID and the PDN ID are carried.

Step 603: the V-PCRF sends the H-PCRF an S9 session establishmentmessage (or the gateway control session establishment message), in whichthe user ID and the PDN ID are carried.

Step 604: the H-PCRF interacts with an SPR according to the user ID andthe PDN ID so as to acquire user subscription data, and makes a PCCpolicy according to a network policy. The PCC policy includes PCC rules,QoS rules, event triggers and so on. The H-PCRF carries the QoS rulesand the event triggers in an S9 session establishment acknowledgementmessage which is sent to the V-PCRF.

Step 605: the V-PCRF sends the ePDG a gateway control sessionestablishment acknowledgement message, in which the QoS rules and theevent triggers are carried.

It should be noted that Step 605 includes Step 605 a and Step 605 b ifthe FMC PF serves as a separate network element entity.

Step 605 a: the V-PCRF sends the FMC PF the gateway control sessionestablishment acknowledgement message, in which the QoS rules and theevent triggers are carried.

Step 605 b: the FMC PF sends the ePDG the gateway control sessionestablishment acknowledgement message, in which the QoS rules and theevent triggers are carried.

Step 606: after the ePDG selects a P-GW, the ePDG sends the P-GW a proxybinding update message, in which the user ID and the PDN ID are carried.

Step 607: the P-GW sends a P-GW IP address update message to the AAAServer and sends the address of the P-GW itself to the AAA Server; thenthe AAA Server interacts with the HSS and saves the address of the P-GWin the HSS.

Step 608: the P-GW allocates an IP address for the UE, and sends theH-PCRF an IP-Connectivity Access Network (IP-CAN) session establishmentindication message in which the user ID, the PDN ID and the IP addressallocated for the UE are carried.

is Step 609: the H-PCRF associates the S9 session established in Step603 with the IP-CAN session requested in Step 609 according to the userID and the PDN ID. The H-PCRF might update the PCC rules and QoS rulesmade in Step 604. The H-PCRF returns an acknowledgement message carryingthe PCC rules to a PCEF.

Step 610: the P-GW returns to the ePDG a proxy binding acknowledgementmessage, in which the IP address allocated for the UE is allocated.

Step 611: the proxy binding is updated successfully, and an IPSec tunnelis established between the UE and the ePDG.

Step 612: the ePDG sends the UE the last IKEv2 signalling in which theIP address of the UE is carried.

Step 613: the V-PCRF determines the BPCF of the fixed broadband accessnetwork accessed by the UE or the entry point of the fixed broadbandaccess network in which the BPCF is located according to the source IPaddress in the IPSec external tunnel information, and sends the BPCF anS9* session establishment message in which the source IP address and thesource port number (if NAT is detected) contained in the IPSec externaltunnel information and the QoS rules are carried.

It should be noted that Step 613 refers to Step 613 a if the FMC PFserves as a separate network element entity.

Step 613 a: the FMC PF determines the BPCF of the fixed broadband accessnetwork accessed by the UE or the entry point of the fixed broadbandaccess network in which the BPCF is located according to the source IPaddress in the IPSec external tunnel information, and sends the BPCF theS9* session establishment message in which the source IP address and thesource port number (if NAT is detected) contained in the IPSec externaltunnel information and the QoS rules are carried.

The execution of this step is triggered after the FMC PF receives thegateway control session establishment message from the ePDG (Step 602).Through this step, the FMC PF senses the access of the UE, triggers thePCRF of the 3GPP access network accessed by the UE to send a policysession request to the BPCF. In this way, QoS control is achieved forthe access of the UE, and thus QoS guarantee is provided to the entiretransmission path of data.

When the fixed broadband access network does not support 3GPP-basedaccess authentication, through this step, QoS control is also achievedfor the access of the UE, and thus QoS guarantee is provided to theentire transmission path of data.

Step 614: the BPCF performs the admission control according to the QoSrules and the access location information of the fixed broadband accessnetwork accessed by the UE, or delegates other network elements of thefixed broadband access network to perform resource admission control(that is, the fixed broadband access network performs the admissioncontrol).

Step 615: the BPCF returns an acknowledgement message to the V-PCRF.

It should be noted that Step 615 refers to Step 615 a if the FMC PFserves as a separate network element entity.

Step 615 a: the BPCF returns an acknowledgement message to the FMC PF.

In other embodiments, the ePDG sends a DHCP request message to theV-PCRF in Step 602, wherein the message is carried with the user ID, thePDN ID and the IPSec external tunnel information. In Step 602 a, theePDG sends the DHCP request message to the FMC PF, wherein the messageis carried with the user ID, the PDN ID and the IPSec external tunnelinformation. In Step 602 b, the FMC PF sends the DHCP request message tothe V-PCRF, wherein the message is carried with the user ID and the PDNID.

Correspondingly, in Step 605, the V-PCRF sends a DHCP acknowledgementmessage to the ePDG, wherein this message is carried with the QoS rulesand the event triggers. In Step 605 a, the V-PCRF sends the DHCPacknowledgement message to the FMC PF, wherein this message is carriedwith the QoS rules and the event triggers. In step 605 b, the FMC PFsends the DHCP acknowledgement message to the ePDG, wherein this messageis carried with the QoS rules and the event triggers.

To sum up, the disclosure is not limited to the messages and protocoltypes interacted between the ePDG and the V-PCRF or between the ePDG andthe FMC PF or between the FMC PF and the V-PCRF.

FIG. 7 shows a diagram illustrating the home routed roaming scene inwhich a UE is accessed to a 3GPP core network through an untrusted fixedbroadband access network according to the disclosure, in which a GTPprotocol is adopted between an ePDG and a P-GW. In FIG. 7, except theaddition of the FMC PF, other network entities and the connectionrelationships therebetween are the same as those in the conventionalart. Therefore, FIG. 7 is easily understood for those skilled in the artand no further description is provided here.

FIG. 8 shows an attachment flowchart in which a UE is accessed to a 3GPPcore network through an untrusted fixed broadband access network basedon the architecture shown in FIG. 7. Referring to FIG. 7 and FIG. 8,supposing an FMC PF is provided in a V-PCRF as the function enhancementof the V-PCRF in this embodiment, the specific implementation includesthe following steps.

Step 801: after the UE is accessed to the fixed broadband access networksystem, the fixed broadband access network system allocates a local IPaddress for the UE. The UE initiates an IKEv2 tunnel establishmentprocess and adopts an EAP to perform authentication. Since thisembodiment is in a roaming scene, the ePDG interacts with an AAA Server(the AAA Server further interacts with an HSS) through an AAA Proxy tocomplete the EAP authentication.

Step 802: the ePDG sends the V-PCRF a gateway control sessionestablishment message, in which the user ID, PDN ID and IPSec externaltunnel information are carried, wherein the IPSec external tunnelinformation includes the source address and the source port of the IKEv2signalling sent from the UE and received by the ePDG.

Since the IKEv2 signalling might be processed with NAT traversal, thesource address and the source port received by the ePDG probably aredifferent from those sent by the UE. For ease of description, the sourceaddress of the UE acquired by the ePDG (including both conditions of NATexisting between the UE and the ePDG and NAT not existing between the UEand the ePDG) is called the UE local IP address. For the condition ofNAT not existing between the UE and the ePDG, the UE local IP addressmay be applied to the fixed broadband access network to locate the UE;if NAT exists, the local address of the UE and the source port numbermay be applied to the fixed broadband access network to locate the UE.If there is no NAT detected, the IPSec external tunnel informationcontains the source IP address only.

It should be noted that Step 802 refers to Step 802 a if the FMC PFserves as a separate network element entity.

Step 802 a: the ePDG sends the FMC PF the gateway control sessionestablishment message, in which the user ID, the PDN ID and the IPSecexternal tunnel information are carried.

Step 803: the V-PCRF returns a gateway control session establishmentacknowledgement message to the ePDG. It should be noted that Step 803refers to Step 803 a if the FMC PF serves as a separate network elemententity.

Step 803 a: the FMC PF returns the gateway control session establishmentacknowledgement message to the ePDG.

Step 804: after the ePDG selects a P-GW, the ePDG sends a bearerestablishment request message to the P-GW, wherein the user ID and thePDN ID are carried.

Step 805: the P-GW sends a P-GW IP address update message to the AAAServer and sends the address of the P-GW itself to the AAA Server; thenthe AAA Server interacts with the HSS and saves the address of the P-GWin the HSS.

Step 806: the P-GW allocates an IP address for the UE, and sends theH-PCRF an IP-CAN session establishment indication message in which theuser ID, the PDN ID and the IP address allocated for the UE are carried.

Step 807: the H-PCRF interacts with an SPR according to the user ID andthe PDN ID, acquires the subscription information of the user and makesa PCC policy. The PCC policy includes PCC rules, event triggers and soon. The PCRF returns an acknowledgement message carrying the PCC rulesand the event triggers to a PCEF.

Step 808: the P-GW returns a bearer establishment acknowledgementmessage to the ePDG, wherein bearer establishment acknowledgementmessage is carried with the IP address allocated for the UE.

Step 809: the bearer is established successfully, and an IPSec tunnel isestablished between the UE and the ePDG.

Step 810: the ePDG sends the UE the last IKEv2 signalling in which theIP address of the UE is carried.

Step 811: the V-PCRF determines the BPCF of the fixed broadband accessnetwork accessed by the UE c or the entry point of the fixed broadbandaccess network in which the BPCF is located according to the source IPaddress in the IPSec external tunnel information, and sends the BPCF anS9* session establishment message in which the source IP address and thesource port number (if NAT is detected) contained in the IPSec externaltunnel information and the QoS rules are carried.

It should be noted that Step 811 refers to Step 811 a if the FMC PFserves as a separate network element entity.

Step 811 a: the FMC PF determines the BPCF of the fixed broadband accessnetwork accessed by the UE or the entry point of the fixed broadbandaccess network in which the BPCF is located according to the source IPaddress in the IPSec external tunnel information, and sends the BPCF theS9* session establishment message in which the source IP address and thesource port number (if NAT is detected) contained in the IPSec externaltunnel information and the QoS rules are carried.

The execution of this step is triggered after the FMC PF receives thegateway control session establishment message from the ePDG (Step 802).Through this step, the FMC PF senses the access of the UE, triggers thePCRF of the 3GPP access network accessed by the UE to send a policysession request to the BPCF. In this way, QoS control is achieved forthe access of the UE, and thus QoS guarantee is provided to the entiretransmission path of data.

When the fixed broadband access network does not support 3GPP-basedaccess authentication, through this step, QoS control is also achievedfor the access of the UE, and thus QoS guarantee is provided to theentire transmission path of data.

Step 812: the BPCF performs the resource admission control according tothe QoS rules (or the QoS information in the QoS rules) and the accesslocation information of the fixed broadband access network accessed bythe UE, or delegates other network elements of the fixed broadbandaccess network to perform the resource admission control (that is, thefixed broadband access network performs the admission control).

Step 813: the BPCF returns an acknowledgement message to the V-PCRF.

It should be noted that Step 813 refers to Step 813 a if the FMC PFserves as a separate network element entity.

Step 813 a: the BPCF returns the acknowledgement message to the FMC PF.

In other embodiments, the ePDG sends a DHCP request message to theV-PCRF in Step 802, wherein the message is carried with the user ID, thePDN ID and the IPSec external tunnel information. In Step 802 a, theePDG sends the DHCP request message to the FMC PF, wherein the messageis carried with the user ID, the PDN ID and the IPSec external tunnelinformation.

Correspondingly, in Step 803, the V-PCRF sends a DHCP acknowledgementmessage to the ePDG. In Step 803 a, the FMC PF sends the DHCPacknowledgement message to the ePDG.

FIG. 9 shows a diagram illustrating the home routed roaming scene inwhich a UE is accessed to a 3GPP core network through an untrusted fixedbroadband access network according to the disclosure, in which the UEadopts a DSMIPv6 protocol. In FIG. 9, except the addition of the FMC PF,other network entities and the connection relationships therebetween arethe same as those in the conventional art. Therefore, FIG. 9 is easilyunderstood for those skilled in the art and no further description isprovided here.

FIG. 10 shows an attachment flowchart in which a UE is accessed to a3GPP core network through an untrusted fixed broadband access networkbased on the architecture shown in FIG. 9. Referring to FIG. 9 and FIG.10, supposing an FMC PF is provided in a V-PCRF as the functionenhancement of the V-PCRF in this embodiment, the specificimplementation includes the following steps.

Step 1001: after the UE is accessed to the fixed broadband accessnetwork system, the fixed broadband access network system allocates alocal IP address for the UE. The UE initiates an IKEv2 tunnelestablishment process and adopts an EAP to perform authentication. Sincethis embodiment is in a roaming scene, the ePDG interacts with an AAAServer (the AAA Server further interacts with an HSS) through an AAAProxy to complete the EAP authentication.

Step 1002: the ePDG sends V-PCRF a gateway control session establishmentmessage, in which the user ID, PDN ID and IPSec external tunnelinformation are carried, wherein the IPSec external tunnel informationincludes the source address and the source port of the IKEv2 signallingsent from the UE and received by the ePDG.

Since the IKEv2 signalling might be processed with NAT traversal, thesource address and the source port received by the ePDG probably aredifferent from those sent by the UE. For ease of description, the sourceaddress of the UE acquired by the ePDG (including both conditions of NATexisting between the UE and the ePDG and NAT not existing between the UEand the ePDG) is called the UE local IP address. For the condition ofNAT not existing between the UE and the ePDG, the UE local IP addressmay be applied to the fixed broadband access network to locate the UE;if NAT exists, the local address of the UE and the source port numbermay be applied to the fixed broadband access network to locate the UE.If there is no NAT detected, the IPSec external tunnel informationcontains the source IP address only.

It should be noted that Step 1002 includes Step 1002 a and Step 1002 bif the FMC PF serves as a separate network element entity.

is Step 1002 a: the ePDG sends the FMC PF the gateway control sessionestablishment message, in which the user ID, the PDN ID and the IPSecexternal tunnel information are carried.

Step 1002 b: the FMC PF sends the V-PCRF the gateway control sessionestablishment message, in which the user ID and the PDN ID are carried.

Step 1003: the V-PCRF sends the H-PCRF an S9 session establishmentmessage (or the gateway control session establishment message), in whichthe user ID and the PDN ID are carried.

Step 1004: the H-PCRF interacts with an SPR according to the user ID andthe PDN ID so as to acquire user subscription data, and makes a PCCpolicy according to a network policy, wherein the PCC policy includesPCC rules, QoS rules, event triggers and so on. The H-PCRF returns an S9session establishment acknowledgement message carrying the QoS rules andthe event triggers to the V-PCRF.

Step 1005: the V-PCRF sends the ePDG a gateway control sessionestablishment acknowledgement message, wherein the QoS rules and theevent triggers are carried.

It should be noted that Step 1005 includes Step 1005 a and Step 1005 bif the FMC PF serves as a separate network element entity.

Step 1005 a: the V-PCRF sends the FMC PF the gateway control sessionestablishment acknowledgement message, wherein the QoS rules and theevent triggers are carried.

Step 1005 b: the FMC PF sends the ePDG the gateway control sessionestablishment acknowledgement, wherein the QoS rules and the eventtriggers are carried.

Step 1006: the ePDG sends the UE the last IKEv2 message in which an IPaddress allocated for the UE is carried, wherein the IP address servesas the Care-of-Address (CoA) of the UE.

Step 1007: an IPSec tunnel is established between the UE and the ePDG.

Step 1008: the UE performs a bootstrapping process. The UE performsDomain Name Server (DNS) search according to an Access Point Name (APN)so as to acquire the IP address of the P-GW of the PDN to be accessed bythe UE. In order to protect the DSMIPv6 message between the UE and theP-GW, the UE establishes a security alliance using the IKEv2 and adoptsthe EAP to perform authentication. The P-GW communicates with the AAAServer (which further interacts with the HSS) to complete the EAPauthentication, meanwhile the P-GW allocates an IPv6 address or a prefixfor the UE which serves as the Home of Address (HoA) of the UE.

Step 1009: the UE sends the P-GW a DSMIPv6 binding update message inwhich the CoA and the HoA are carried, wherein the life cycle parameterin the binding message is not 0. The P-GW establishes a binding context.

Step 1010: a PCEF in the P-GW sends the H-PCRF an IP-CAN sessionestablishment indication message, wherein the user ID and the PDN ID arecarried.

Step 1011: the H-PCRF associates the S9 session established in Step 1003with the IP-CAN session requested to be established in Step 1010according to the user ID and the PDN ID. The H-PCRF might update the PCCrules and QoS rules made in Step 1004. The H-PCRF returns to the PCEF anacknowledgement message, in which the PCC rules are carried.

Step 1012: the P-GW returns a binding acknowledgement message to the UE.

Step 1013: the V-PCRF determines the BPCF of the fixed broadband accessnetwork accessed by the UE or the entry point of the fixed broadbandaccess network in which the BPCF is located according to the source IPaddress in the IPSec external tunnel information, and sends an S9*session establishment message to the BPCF, wherein the S9* sessionestablishment message is carried with the source IP address and thesource port number (if NAT is detected) contained in the IPSec externaltunnel information and the QoS rules.

It should be noted that Step 1013 refers to Step 1013 a if the FMC PFserves as a separate network element entity. Step 1013 a: the FMC PFdetermines the BPCF of the fixed broadband access network accessed bythe UE or the entry point of the fixed broadband access network in whichthe BPCF is located according to the source IP address in the IPSecexternal tunnel information, and sends the S9* session establishmentmessage to the BPCF, wherein the S9* session establishment message iscarried with the source IP address and the source port number (if NAT isdetected) contained in the IPSec external tunnel information and the QoSrules.

The execution of this step is triggered after the FMC PF receives thegateway control session establishment message from the ePDG (Step 1002).Through this step, the FMC PF senses the access of the UE, triggers thePCRF of the 3GPP access network accessed by the UE to send a policysession request to the BPCF. In this way, QoS control is achieved forthe access of the UE, and thus QoS guarantee is provided to the entiretransmission path of data.

When the fixed broadband access network does not support 3GPP-basedaccess authentication, QoS control is also achieved for the access ofthe UE through this step, and thus QoS guarantee is provided to theentire transmission path of data.

Step 1014: the BPCF performs resource admission control according to theQoS rules and the access location information of the fixed broadbandaccess network accessed by the UE, or delegates other network elementsof the fixed broadband access network to perform resource admissioncontrol (that is, the fixed broadband access network performs theadmission control).

Step 1015: the BPCF returns an acknowledgement message to the V-PCRF.

It should be noted that Step 1015 refers to Step 1015 a if the FMC PFserves as a separate network element entity. Step 1015 a: the BPCFreturns the acknowledgement message to the FMC PF.

In other embodiments, the ePDG sends a DHCP request message to theV-PCRF in Step 1002, wherein the message is carried with the user ID,the PDN ID and the IPSec external tunnel information. In Step 1002 a,the ePDG sends the DHCP request message to the FMC PF, wherein themessage is carried with the user ID, the PDN ID and the IPSec externaltunnel information. In Step 1002 b, the FMC PF sends the DHCP requestmessage to the V-PCRF, wherein the message is carried with the user IDand the PDN ID.

Correspondingly, in Step 1005, the V-PCRF sends a DHCP acknowledgementmessage to the ePDG, wherein this message is carried with the QoS rulesand the event triggers. In Step 1005 a, the V-PCRF sends the DHCPacknowledgement message to the FMC PF, wherein this message c is carriedwith the QoS rules and the event triggers. In step 1005 b, the FMC PFsends the DHCP acknowledgement message to the ePDG, wherein this messageis carried with the QoS rules and the event triggers.

FIG. 11 shows a diagram illustrating the local breakout roaming scene inwhich a UE is accessed to a 3GPP core network through an untrusted fixedbroadband access network according to the disclosure, in which a GTP orPMIPv6 protocol is adopted between an ePDG and a P-GW. In FIG. 11,except the addition of FMC PF, other network entities and the connectionrelationships therebetween are the same as those in the conventionalart. Therefore, FIG. 11 is easily understood for those skilled in theart and no further description is provided here.

FIG. 12 shows an attachment flowchart in which a UE is accessed to a3GPP core network through an untrusted fixed broadband access networkbased on the architecture shown in FIG. 11. Referring to FIG. 11 andFIG. 12, supposing an FMC PF is provided in a V-PCRF as the functionenhancement of the V-PCRF in this embodiment, the specificimplementation includes the following steps.

The specific implementation of Step 1201 to Step 1205 is the same asthat of Step 601 to Step 605, and no further description is repeatedhere.

Step 1206: after the ePDG selects the Visited P-GW, the ePDG sends theP-GW a proxy binding update or session establishment request message, inwhich the user ID and the PDN ID are carried.

Step 1207: the P-GW sends a P-GW IP address update message to the AAAServer through the AAA proxy and sends the address of the P-GW itself tothe AAA Server, then the AAA Server interacts with the HSS and saves theaddress of the P-GW in the HSS.

is Step 1208: the P-GW allocates an IP address for the UE, and sends theV-PCRF an IP-CAN session establishment indication message, wherein theuser ID, the PDN ID and the IP address allocated for the UE are carried.The V-PCRF associates the gateway control session established in Step1202 with the IP-CAN session established in Step 1208 according to theuser ID and the PDN ID.

In other embodiments, if the message sent in Step 1202 from the ePDG tothe PCRF is a DHCP request message, then the V-PCRF associates the DHCPrequest message in Step 1202 with the message in Step 1208.

It should be noted that Step 1208 includes Step 1208 a and Step 1208 bif the FMC PF serves as a separate network element entity.

Step 1208 a: the V-PCRF sends the H-PCRF an S9 session modificationmessage, in which the allocated IP address is carried.

Step 1208 b: H-PCRF might update the PCC rules made in Step 1204 andreturns them to the V-PCRF.

Step 1209: the V-PCRF sends the PCEF an IP-CAN session establishmentacknowledgement message, wherein the PCC rules are carried.

Step 1210: the P-GW returns a proxy binding update message or a sessionestablishment acknowledgement message to the ePDG.

The specific implementation of Step 1211 to Step 1215 is totally thesame as that of Step 611 to Step 615 and no further description isrepeated here.

FIG. 13 shows a diagram illustrating the local breakout roaming scene inwhich a UE is accessed to a 3GPP core network through an untrusted fixedbroadband access network according to the disclosure, in which the UEadopts a DSMIPv6 protocol for access. In

FIG. 13, except the addition of FMC PF, other network entities and theconnection relationships therebetween are the same as those in theconventional art. Therefore, FIG. 13 is easily understood for thoseskilled in the art and no further description is provided here.

FIG. 14 shows an attachment flowchart in which a UE is accessed to a3GPP core network through an untrusted fixed broadband access networkbased on the architecture shown in FIG. 13. Referring to FIG. 13 andFIG. 14, supposing an FMC PF is provided in a V-PCRF as the functionenhancement of the V-PCRF in this embodiment, the specificimplementation includes the following steps.

The specific implementation of Step 1401 to Step 1407 is totally thesame as that of Step 1001 to Step 1007, and no further description isrepeated here.

Step 1408: the UE performs a bootstrapping process. The UE performs DNSsearch according to an APN so as to acquire the IP address of the P-GWof the PDN to be accessed by the UE, wherein the P-GW is located in avisited place. In order to protect the DSMIPv6 message between the UEand the P-GW, the UE establishes a security alliance using the IKEv2 andadopts the EAP to perform authentication. The P-GW communicates with theAAA Server (the AAA Server further interacts with the HSS) through theAAA proxy to complete the EAP authentication, meanwhile the P-GWallocates an IPv6 address or a prefix for the UE which serves as the HoAof the UE.

Step 1409: the UE sends the P-GW a DSMIPv6 binding update message inwhich the CoA and the HoA are carried, wherein the life cycle parameterin the binding message is not 0. The P-GW establishes a binding context.

Step 1410: a PCEF in the P-GW sends the V-PCRF an IP-CAN sessionestablishment indication message, wherein the user ID and the PDN ID arecarried. The V-PCRF associates the gateway control session in Step 1402with the IP-CAN session in Step 1410 according to the user ID.

In other embodiments, if the message sent in Step 1402 from the ePDG tothe PCRF is a DHCP request message, then the V-PCRF associates the DHCPrequest message in Step 1402 with the message in Step 1410.

It should be noted that Step 1410 includes Step 1410 a and Step 1410 bif the FMC PF serves as a separate network element entity.

Step 1410 a: the V-PCRF sends the H-PCRF an S9 session modificationmessage in which the IP address is carried.

Step 1410 b: the H-PCRF makes PCC rules. The H-PCRF returns the PCCrules to the V-PCRF.

The specific implementation of Step 1411 to Step 1415 is totally thesame as that of Step 1011 to Step 1015, and no further description isrepeated here.

FIG. 15 shows a diagram illustrating the non-roaming scene in which a UEis accessed to a 3GPP core network through an untrusted fixed broadbandaccess network according to the disclosure, in which a GTP or PMIPv6protocol is adopted between an ePDG and a P-GW. For the attachment flowbased on this architecture, it is only needed to use a PCRF to replacethe V-PCRF in the process of FIG. 12 and to avoid all the interactionprocesses between the V-PCRF and the H-PCRF. FIG. 16 shows a diagramillustrating the non-roaming scene in which a UE is accessed to a 3GPPcore network through an untrusted fixed broadband access networkaccording to the disclosure, in which the UE adopts a DSMIPv6 protocolto perform access. For the attachment flow based on this architecture,it is only needed to use a PCRF to replace the V-PCRF in the process ofFIG. 14 and to avoid all the interaction processes between the V-PCRFand the H-PCRF. The specific implementation of the flow is easilyunderstood by those skilled in the art according to the aboveembodiments and no further description is provided here.

After the UE is accessed to the 3GPP core network through the fixedbroadband access network, the policy may change. For instance, the PCRF(or a Home PCRF (H-PCRF) in a roaming scene) makes a policy afterreceiving service information provided by an AF or a resourcemodification request message initiated by the UE, and the BPCF isrequested to authorize bandwidth after the FMC PF receives changed PCCrules, then the BPCF performs the resource admission control accordingto the request. A detailed description is provided below in conjunctionwith embodiments.

FIG. 17 shows a flowchart in which an H-PCRF requests a BPCF to performthe admission control when making polices in the home routed roamingscene (the architectures of FIG. 5 and FIG. 9) according to thedisclosure. Supposing an FMC PF is provided in a V-PCRF as the functionenhancement of the V-PCRF in this embodiment, the specific processincludes the following steps.

Step 1701: the H-PCRF makes a policy after receiving the serviceinformation provided by an AF or a resource modification request messageinitiated by a UE, wherein the policy decision may be made through thefollowing three ways.

Way 1: if the AF provides new service information or the UE initiates anew resource allocation request, then the H-PCRF performs QoSauthorization and makes PCC rules and corresponding QoS rules. The QoSinformation of the PCC rules and the QoS rules include QoS ClassIdentifier (QCI), ARP (Allocation and Retention Priority), GBR(Guaranteed Bit Rate) and Maximum Bit Rate (MBR).

Way 2: if the AF notifies termination of service or the UE initiates aresource release request, the H-PCRF performs QoS authorization, anddecides to delete or deactivate corresponding PCC rules and QoS rules,wherein the QoS information of the PCC rules and the QoS rules to bedeleted or deactivated includes QCI, ARP, GBR and MBR.

Way 3: if the AF modifies the service information already provided orthe UE requests to modify the resource already allocated, then theH-PCRF performs QoS authorization and updates the made PCC rules and QoSrules, wherein the PCC rules and the QoS information of the QoS rulesincludes QCI, ARP, GBR and MBR.

Step 1702: the H-PCRF sends an S9 session rules supply message to theV-PCRF.

If the H-PCRF makes a policy through Way 1, then the H-PCRF carries theinformation of newly made QoS rules in the S9 session rules supplymessage.

If the H-PCRF makes a policy through Way 2, then the H-PCRF carries theinformation that indicates delete or deactivate the QoS rules in the S9session rules supply message.

If the H-PCRF makes a policy through Way 3, then the H-PCRF carries theinformation of the updated QoS rules in the S9 session rules supplymessage.

Step 1703: the V-PCRF sends a QoS authorization request message to theBPCF to request the BPCF to perform QoS authorization.

If the H-PCRF makes a policy through Way 1, then the V-PCRF carries inthe QoS authorization request message an indication of requesting toallocate resources and the GBR contained in the QoS information, so asto request the BPCF to allocate the bandwidth resource GBR.

If the H-PCRF makes a policy through Way 2, then the V-PCRF carries inthe QoS authorization request message an indication of requesting torelease resources and the GBR contained in the QoS information, so as torequest the BPCF to release the bandwidth resource GBR.

If the H-PCRF makes a policy through Way 3, then the V-PCRF would sendthe request to the BPCF according to the increment (difference) betweenthe GBR contained in the updated QoS information and the GBR alreadyallocated. If the GBR after update is reduced relative to the GBRalready allocated, the GBR that the V-PCRF carries in the QoSauthorization request message is the increment of the GBR and the V-PCRFcarries an indication of requesting to release resources in the QoSauthorization request message. If the GBR after update is increasedrelative to the allocated GBR, the GBR that the V-PCRF carries in theQoS authorization request message is the increment of the GBR and theV-PCRF carries an indication of requesting to allocate resources in theQoS authorization request message. It should be noted that Step 1703includes Step 1703 a and Step 1703 b if the FMC PF serves as a separatenetwork element entity.

Step 1703 a: the V-PCRF sends the FMC PF a gateway control and QoS rulessupply message, which is carried with the information received by theV-PCRF from the H-PCRF.

Step 1703 b: the FMC PF sends the QoS authorization request message tothe BPCF to request the BPCF to perform QoS authorization, wherein thecontent thereof is the same as that in Step 1703.

Step 1704: the BPCF implements a corresponding policy according to therequest message from the V-PCRF.

If the BPCF receives a request for allocating the bandwidth resourceGBR, the BPCF performs the resource admission according to the currentlyavailable bandwidth of a subscribed fixed-network line. If the restavailable bandwidth is greater than or equal to the GBR, the BPCFaccepts the request of the V-PCRF and returns an acceptanceacknowledgement message to the V-PCRF, and meanwhile, the BPCF deductsthe GBR from the currently available bandwidth of the subscribedfixed-network line. If the rest available bandwidth is less than GBR,the BPCF rejects the request of the V-PCRF, returns a rejection messagecarrying the bandwidth that the BPCF can accept to the V-PCRF.

If the BPCF receives a request for releasing the bandwidth resource GBR,the BPCF returns an acceptance acknowledgement message directly, andmeanwhile the BPCF adds the GBR to the currently available bandwidth ofthe subscribed fixed-network line.

In addition, the V-PCRF or FMC PF can provide to the BPCF the QoS ruleswhich are provided by the H-PCRF. The BPCF decides whether to accept orreject the QoS authorization request after performing the resourceadmission control (When performing the resource admission control, theBPCF would also consider the QCI and/or ARP comprehensively besidesconsidering whether the currently available rest bandwidth can meet therequested bandwidth).

The BPCF may also forward the request message from the V-PCRF to othernetwork elements (for example, BNG) of the fixed broadband accessnetwork, and then this network element implements similar policy andreturns the resource admission result to the BPCF.

Step 1705: the BPCF returns to the V-PCRF a QoS authorization requestacknowledgement message in which the information of the policyimplemented in Step 1704 is carried.

It should be noted that Step 1705 includes Step 1705 a and Step 1705 bif the FMC PF serves as a separate network element entity.

Step 1705 a: the BPCF returns to the FMC PF the QoS authorizationrequest acknowledgement message in which the information of the policyimplemented in Step 1704 is carried.

Step 1705 b: the FMC PF makes a policy according to the message returnedfrom the BPCF.

If the FMC PF receives an acceptance acknowledgement message (includingreceiving resource allocation and resource release), then the FMC PFexecutes Step 1705 c and an acceptance indication is carried.

If the FMC PF receives a rejection message, the V-PCRF would performresource pre-emption according to the ARP in the QoS information, theresource pre-emption including the following logic judgments: the FMC PFcompares, according to the ARP, this QoS information with otherauthorized QoS information of the user and with the authorized QoSinformation of all other users who are accessed through the samebroadband line, if this QoS information can not pre-empt the resourcesof other QoS information, then the FMC PF executes Step 1705 c and arejection indication is carried; if the QoS information can pre-empt theresources of the authorized QoS information of other users, then the FMCPF initiates a process of authorizing pre-empted QoS information (thisprocess may be implemented through an existing process of deleting anddeactivating QoS rules). In addition, the FMC PF sends again a broadbandsession QoS request message to the BPCF, the BPCF allocates thebandwidth and sends an acknowledgement message, and the FMC PF executesStep 1705 c and an acceptance indication is carried.

Step 1706: the V-PCRF makes a policy according to the message returnedfrom the BPCF.

If the V-PCRF receives an acceptance acknowledgement message (includingreceiving resource allocation and resource release), then the V-PCRFexecutes Step 1707 and an acceptance indication is carried.

If the V-PCRF receives a rejection message, the V-PCRF would perform thefollowing logic judgments according to the ARP in the QoS information:the V-PCRF compares, according to the ARP, this QoS information withother authorized QoS information of the user and with the authorized QoSinformation of all other users who are accessed through the samebroadband line, if this QoS information can not pre-empt the resourcesof other QoS information, then the V-PCRF executes Step 1707 and arejection indication is carried; if the QoS information can pre-empt theresources of the authorized QoS information of other users, the V-PCRFinitiates a process of authorizing pre-empted QoS information (thisprocess may be implemented through an existing process of deleting anddeactivating QoS rules). In addition, the V-PCRF sends again a broadbandsession QoS request message to the BPCF, the BPCF allocates thebandwidth and sends an acknowledgement message, and the V-PCRF executesStep 1707 and an acceptance indication is carried.

Step 1707: the V-PCRF returns an S9 session rules supply acknowledgementmessage to the H-PCRF to notify the H-PCRF whether the request isaccepted or rejected.

Step 1708: if the returned message is an acceptance indication, theH-PCRF sends the PCEF a policy and charging rules supply messagecarrying the PCC rules.

Step 1709: the PCEF returns an acknowledgement message to the H-PCRF.

FIG. 18 shows a flowchart in which an H-PCRF requests a BPCF to performthe admission control when making polices in the local breakout roamingscene (the architecture of FIG. 11 and FIG. 13) according to thedisclosure. Supposing an FMC PF is provided in a V-PCRF as the functionenhancement of the V-PCRF in this embodiment, the specific processincludes the following steps.

Step 1801: the H-PCRF makes a policy after receiving the serviceinformation provided by an AF or a resource modification request messageinitiated by a UE, wherein the policy decision may be made through thefollowing three ways.

Way 1: if the AF provides new service information or the UE initiates anew resource allocation request, then the H-PCRF performs QoSauthorization and makes PCC rules. The QoS information of the PCC rulesincludes QCI, ARP, GBR and MBR.

Way 2: if the AF notifies termination of service or the UE initiates aresource release request, the H-PCRF performs QoS authorization, anddecides to delete or deactivate corresponding PCC rules, wherein the QoSinformation of the PCC rules to be deleted or deactivated includes QCI,ARP, GBR and MBR.

Way 3: if the AF modifies the service information already provided orthe UE requests to modify the resource already allocated, then theH-PCRF performs QoS authorization and updates the made PCC rules,wherein the QoS information of the PCC rules and the QoS rules includesQCI, ARP, GBR and MBR.

Step 1802: the H-PCRF sends an S9 session rules supply message to theV-PCRF.

If the H-PCRF makes a policy through Way 1, then the H-PCRF carries theinformation of newly made PCC rules in the S9 session rules supplymessage.

If the H-PCRF makes a policy through Way 2, then the H-PCRF carries theinformation that indicates to delete or deactivate the PCC rules in theS9 session rules supply message.

If the H-PCRF makes a policy through Way 3, then the H-PCRF carries theinformation of the updated PCC rules in the S9 session rules supplymessage.

The specific implementation of Step 1803 to Step 1806 is totally thesame as that of Step 1703 to Step 1706, and no further description isrepeated here.

Step 1807: if the V-PCRF receives an acceptance indication, the V-PCRFsends a policy and charging rules supply message carried with the PCCrules to the PCEF.

Step 1808: the PCEF returns an acknowledgement message to the V-PCRF.

Step 1809: the V-PCRF returns an S9 session rules supply acknowledgementmessage to the H-PCRF to notify the H-PCRF whether the request isaccepted or rejected.

FIG. 19 shows a flowchart in which an H-PCRF requests a BPCF to performthe admission control when making polices in the home routed roamingscene (the architecture of FIG. 7) according to the disclosure.Supposing an FMC PF is provided in a V-PCRF as the function enhancementof the V-PCRF in this embodiment, the specific process includes thefollowing steps.

Step 1901: the H-PCRF makes a policy after receiving the serviceinformation provided by an AF or a resource modification request messageinitiated by a UE, wherein the policy decision may made through thefollowing three ways.

Way 1: if the AF provides new service information or the UE initiates anew resource allocation request, then the H-PCRF performs QoSauthorization and makes PCC rules. The QoS information of the PCC rulesincludes QCI, ARP, GBR and MBR.

Way 2: if the AF notifies termination of service or the UE initiates aresource release request, the H-PCRF performs QoS authorization, anddecides to delete or deactivate corresponding PCC rules, wherein the QoSinformation of the PCC rules to be deleted or deactivated includes QCI,ARP, GBR and MBR.

Way 3: if the AF modifies the provided service information or the UErequests to modify the resource already allocated, then the H-PCRFperforms QoS authorization and updates the made PCC rules, wherein theQoS information of the PCC rules includes QCI, ARP, GBR and MBR.

Step 1902: the H-PCRF sends the P-GW a policy and charging rules supplymessage carried with the PCC rules.

Step 1903: the P-GW executes the PCC rules and executes bearing binding.

Step 1904: the P-GW sends a bearer establishment request or a bearerupdate request or a bearer delete request to the ePDG according to theresult of bearer binding, and the QoS information is carried in themessage.

Step 1905: the ePDG sends a gateway control and QoS rules requestmessage to the V-PCRF, wherein the QoS information is carried in thegateway control and QoS rules request message.

If the message received by the ePDG is a bearer establishment request,the ePDG carries in the gateway control and QoS rules request message anindication of requesting to allocate resources and the GBR contained inthe QoS information, so as to request the V-PCRF to allocate thebandwidth resource GBR.

If the message received by the ePDG is a bearer delete request, the ePDGcarries in the gateway control and QoS rules request message anindication of requesting to release resources and the GBR contained inthe QoS information, so as to request the V-PCRF to release bandwidthresource GBR.

If the message received by the ePDG is a bearer update request, the ePDGwould send a request to the V-PCRF according to the increment betweenthe GBR contained in the updated QoS information and the GBR alreadyallocated. If the GBR after update is reduced relative to the GBRalready allocated, the GBR that the ePDG carries in the gateway controland QoS rules request message is the increment of the GBR and the ePDGcarries an indication of requesting to release resources in the gatewaycontrol and QoS rules request message. If the GBR after update isincreased relative to the GBR already allocated, the GBR that the ePDGcarries in the gateway control and QoS rules request message is theincrement of the GBR and the ePDG carries an indication of requesting toallocate resources in the gateway control and QoS rules request message.

Step 1906: the V-PCRF sends the BPCF a QoS authorization request carriedwith the QoS information acquired in Step 1905.

Step 1907: the BPCF implements a corresponding policy according to therequest message from the V-PCRF.

If the BPCF receives a request for allocating bandwidth resource GBR,the BPCF performs the resource admission according to the currentlyavailable bandwidth of a subscribed fixed-network line. If the restavailable bandwidth is greater than or equal to the GBR, the BPCFaccepts the request of the V-PCRF and returns an acceptanceacknowledgement message to the V-PCRF, and meanwhile, the BPCF deductsthe GBR from the currently available bandwidth of the subscribedfixed-network line. If the rest available bandwidth is less than GBR,the BPCF rejects the request of the V-PCRF, returns a rejection messagecarrying the bandwidth that the BPCF can accept to the V-PCRF.

If the BPCF receives a request for releasing bandwidth resource GBR, theBPCF returns an acceptance acknowledgement message directly, andmeanwhile the BPCF adds the GBR to the currently available bandwidth ofthe subscribed fixed-network line.

In addition, the QoS information provided to the V-PCRF or FMC PF by theePDG may also include QCI, ARP and the like, and the V-PCRF or FMC PFmay further provide this information to the BPCF. The BPCF decideswhether to accept or reject the QoS authorization request afterperforming the resource admission control (when performing the resourceadmission control, the BPCF would also consider the QCI and/or ARPcomprehensively besides considering whether the currently available restbandwidth can meet the requested bandwidth).

Step 1908: the BPCF returns to the V-PCRF a QoS authorization requestacknowledgement message carried with the information of the policyimplemented in Step 1907.

Step 1909: the V-PCRF makes a policy according to the message returnedfrom the BPCF.

If the V-PCRF receives an acceptance acknowledgement message (includingreceiving resource allocation and resource release), the V-PCRF executesStep 1910 and an acceptance indication is carried.

If the V-PCRF receives a rejection message, the V-PCRF would perform thefollowing logic judgments according to the ARP in the QoS information:the V-PCRF compares, according to the ARP, this QoS information withother authorized QoS information of the user and with the authorized QoSinformation of all other users who are accessed through the samebroadband line, if this QoS information can not pre-empt the resource ofother QoS information, then the V-PCRF executes Step 1910 and arejection indication is carried; if the QoS information can pre-empt theresources of the authorized QoS information of other users, then theV-PCRF initiates a process of authorizing pre-empted QoS information(this process may be implemented through an existing process of deletingand deactivating QoS rules). In addition, the V-PCRF sends again abroadband session QoS request message to the BPCF, the BPCF allocatesthe bandwidth and sends an acknowledgement message, and the V-PCRFexecutes Step 1910 and an acceptance indication is carried.

Step 1910: the V-PCRF returns to the ePDG an acknowledgement messagecarried with the acceptance or rejection indication.

It should be noted that Step 1905 a to Step 1910 a is executed toreplace the above Step 1905 to Step 1910 if the FMC PF serves as aseparate network element entity, wherein Step 1905 a to Step 1910 a issimilar to Step 1905 to Step 1910, and the difference lies in that theFMC PF is adopted to replace the V-PCRF.

Step 1911: the ePDG returns to the P-GW an acknowledgement messagecarried with an acceptance or rejection message.

In the scene of non-roaming (FIG. 15 and FIG. 16), for the process ofthe PCRF requesting the BPCF to perform the admission control whenmaking polices, it is only needed to use the PCRF to replace the V-PCRFin the process of FIG. 18 and to avoid all the interaction processesbetween the V-PCRF and the H-PCRF.

The disclosure is not limited to the protocol and message types (forexample, Diameter, Remote Authentication Dial In User Service (RADIUS),DHCP protocol and GPRS Tunnel Protocol (GTP)) interacted between theePDG and the PCRF, between the ePDG and the V-PCRF or between the ePDGand the FMC PF. The purpose of the ePDG sending a message to the PCRF,V-PCRF or FMC PF is to trigger the PCRF, V-PCRF or FMC PF to initiate anestablishment of S9* session with the BPCF and provide necessaryinformation.

The above are only preferred embodiments of the disclosure and are notintended to limit the scope of protection of the disclosure. Anymodification, equivalent substitute and improvement made within the sprinciple of the disclosure are deemed to be included within the scopeof protection of the disclosure.

1. A policy control method for accessing a fixed broadband access network, comprising: a Fixed Mobile Convergence Policy Function (FMC PF) is set in a mobile network which a user requests to be accessed to, after the FMC PF receives a trigger message from an Evolved Packet Data Gateway (ePDG), requesting, by the FMC PF, a Broadband Policy Control Framework (BPCF) in the fixed broadband access network to establish a policy control session; and performing, by the fixed broadband access network, admission control according to Quality of Service (QoS) rules or QoS information transmitted from the FMC PF through the policy control session.
 2. The policy control method according to claim 1, wherein the FMC PF serves as a separate function entity, or is integrated in a Policy and Charging Rules Function (PCRF).
 3. The policy control method according to claim 1, wherein the trigger message received by the FMC PF from the ePDG is: a gateway control session establishment message carrying Internet Protocol Security (IPSec) external tunnel information or a Dynamic Host Configuration Protocol (DHCP) request message carrying IPSec external tunnel information; wherein the IPSec external tunnel information comprises a User Equipment (UE) local IP address received by the ePDG.
 4. The policy control method according to claim 3, wherein requesting, by the FMC PF, the BPCF to establish a policy control session comprises: determining, by the FMC PF, the BPCF of the fixed broadband access network accessed by the UE or the entry point of the fixed broadband access network in which the BPCF is located according to the UE local IP address, and sending, by the FMC PF, an S9* session establishment message to the BPCF, wherein the S9* session establishment message is carried with the IPSec external tunnel information.
 5. The policy control method according to claim 3, wherein the IPSec external tunnel information comprises a source port number.
 6. The policy control method according to claim 1, wherein when the user is a non-roaming user, the mobile network which the user requests to be accessed to is the Public Land Mobile Network (PLMN) to which the user belongs; when the user is a roaming user, the mobile network which the user requests to be accessed to is the PLMN that the user visits.
 7. The policy control method according to claim 1, wherein requesting to establish a policy control session and performing, by the fixed broadband access network, admission control comprise: after the FMC PF acquires Policy and Charging Control (PCC) rules, QoS rules or a QoS request, transmitting, by the FMC PF, the QoS rules or QoS information to the BPCF through the policy control session.
 8. The policy control method according to claim 7, wherein the FMC PF serves as a separate function entity, acquiring, by the FMC PF, the QoS rules or the QoS information comprises: acquiring, by the FMC PF, the PCC rules or the QoS rules from a PCRF; or acquiring, by the FMC PF, the QoS request from the ePDG.
 9. The policy control method according to claim 7, wherein the FMC PF is integrated in a PCRF; acquiring, by the FMC PF, the PCC rules, the QoS rule or the QoS request comprises: when the user is a non-roaming user, making the PCC rules and/or the QoS rules by the PCRF; when the user is a roaming user, acquiring, by the PCRF, the PCC rules or the QoS rules from a PCRF of the PLMN to which the user belongs; or acquiring, by the PCRF, the QoS request from the ePDG.
 10. The policy control method according to claim 8, wherein performing, by the fixed broadband access network, resource admission control according to a request comprises: if the BPCF receives a request for allocating bandwidth resource GBR (Guaranteed Bit Rate), performing, by the fixed broadband access network, the resource admission control according to the currently available bandwidth of a subscribed fixed-network line: when the rest available bandwidth is greater than or equal to the GBR, accepting, by the fixed broadband access network, the request of the FMC PF of the mobile network which the user requests to be accessed to; returning, by the fixed broadband access network, an acceptance acknowledgement message to the FMC PF of the mobile network which the user requests to be accessed to; and deducting, by the fixed broadband access network, the GBR from the currently available bandwidth of the subscribed fixed-network line, when the rest available bandwidth is less than the GBR, rejecting, by the fixed broadband access network, the request of the FMC PF of the mobile network which the user requests to be accessed to; and returning, by the fixed broadband access network, a rejection message to the FMC PF of the mobile network which the user requests to be accessed to, wherein the rejection message is carried with the bandwidth that the fixed broadband access network can accept, if the BPCF receives a request for releasing the bandwidth resource GBR, returning, by the BPCF, an acceptance acknowledgement message; and adding, by the fixed broadband access network, the GBR to the currently available bandwidth of the subscribed fixed-network line.
 11. The policy control method according to claim 10, wherein if the FMC PF receives the rejection message, the method further comprising: performing, by the FMC PF, resource pre-emption according to an Allocation and Retention Priority (ARP).
 12. A policy control system for accessing a fixed broadband access network, at least comprising an Evolved Packet Data Gateway (ePDG), a Fixed Mobile Convergence Policy Function (FMC PF) and a Broadband Policy Control Framework (BPCF), wherein the ePDG is configured to send a trigger message to the FMC PF; the FMC PF is set in a mobile network which a user requests to be accessed to and is configured to receive the trigger message from the ePDG and to request the BPCF to establish a policy control session; and the BPCF is configured to receive the request from the FMC PF and to perform admission control according to QoS rules or QoS information transmitted through the policy control session or to delegate another network element of the fixed broadband access network to perform the admission control.
 13. The policy control system according to claim 12, wherein the FMC PF is configured to acquire PCC rules, QoS rules or a QoS request containing GBR, and to transmit the QoS rules or QoS information to the BPCF through the policy control session.
 14. The policy control system according to claim 13, wherein the FMC PF serves as a separate function entity, the system further comprising a PCRF which is configured to provide the PCC rules or the QoS rules to the FMC PF; or the ePDG is further configured to provide the QoS request to the FMC PF.
 15. The policy control system according to claim 12, wherein the FMC PF is integrated in a PCRF, the PCRF is configured to make PCC rules or QoS rules when the user is a non-roaming user, and to acquire the PCC rules or the QoS rules from a PCRF of the PLMN to which the user belongs when the user is a roaming user; or the PCRF is configured to acquire the QoS request from the ePDG.
 16. The policy control system according to claim 13, wherein when the FMC PF receives a rejection message from the BPCF, the FMC PF is configured to perform resource pre-emption according to an ARP.
 17. The policy control method according to claim 4, wherein the IPSec external tunnel information comprises a source port number.
 18. The policy control method according to claim 9, wherein performing, by the fixed broadband access network, resource admission control according to a request comprises: if the BPCF receives a request for allocating bandwidth resource GBR (Guaranteed Bit Rate), performing, by the fixed broadband access network, the resource admission control according to the currently available bandwidth of a subscribed fixed-network line: when the rest available bandwidth is greater than or equal to the GBR, accepting, by the fixed broadband access network, the request of the FMC PF of the mobile network which the user requests to be accessed to; returning, by the fixed broadband access network, an acceptance acknowledgement message to the FMC PF of the mobile network which the user requests to be accessed to; and deducting, by the fixed broadband access network, the GBR from the currently available bandwidth of the subscribed fixed-network line, when the rest available bandwidth is less than the GBR, rejecting, by the fixed broadband access network, the request of the FMC PF of the mobile network which the user requests to be accessed to; and returning, by the fixed broadband access network, a rejection message to the FMC PF of the mobile network which the user requests to be accessed to, wherein the rejection message is carried with the bandwidth that the fixed broadband access network can accept, if the BPCF receives a request for releasing the bandwidth resource GBR, returning, by the BPCF, an acceptance acknowledgement message; and adding, by the fixed broadband access network, the GBR to the currently available bandwidth of the subscribed fixed-network line.
 19. The policy control method according to claim 18, wherein if the FMC PF receives the rejection message, the method further comprising: performing, by the FMC PF, resource pre-emption according to an Allocation and Retention Priority (ARP). 